Piston



Nov. 3, 1931.

A. L. NELSON PISTON Original Filed Aug. 18, 1927 2 Sheets-Sheet l Nov. 3, 1931. A. NELSON 1,830,172

PISTON Original Filed Aug. 18, 1927 2 Sheets-Sheet 2 Patented Nov. 3, 1931 UNITED STATES PATENT OFFICE ADOLPE L'IN'ELBON', OI DETROIT, MICHIGAN, ASSIGNOB TO BOBZN' Q BRASS CORPORATION, OF DETROIT, MICHIGAN IPISTOH Lpplleaflon fled August 18, 1927, Serial No. 213,787. Renewed September 8, 1880.

This invention relates to engine pistons,

particularly to the type used in internal comustion engines, an aims to improve the construction of such pistons.

A particular object is the provision of a piston of light-weight material having its expansion controlled by struts of relatlvely inexpansiblematerial, the skirt of the piston having an improved construction so as to m obtain as near uniform stifiness in all directions as possible.

The invention involves the. use of arcshaped inwardly directed flanges at the bottom edge of the piston skirt in order to rovide stillness at the desired points. T ese flanges also provide a surface that may be bored out for machining purposes, and hence theskirt wall may be made thinner than it otherwise could be.

2 Another feature of the invention resides in the arrangement of the struts with relation to the upper end of the piston skirt so as to give the piston the desired fit under operating conditions.

35 ,While preferred embodiments of the invention have been disclosed for purposes of illustration, it should be understood that various changes can be made in the structure without departing from the spirit and scope of the invention as hereinafter set forth and claimed.

In the drawings: Fig. 1 is an elevationv partly in section of a piston embodying the invention.

Fig. 2 is a section taken on line 2-2 of Fig. 1.

Fig. 3 is a section taken on line 3-3 of Fig. 4.

Fig. 4 is a view similar to Fig. 1 showing a modified form of piston.

Fig; 5 is a section through the bottom end of the. piston illustrating the method of manufacture.

Fig. 6 is a diagram illustrating the expansion of the skirt.

Fig. 7 is a diagram illustrating the action of the skirt with a certain vertical location of the struts.

Fig. 8 is a diagram similar to Fig. 7 for a different strut location.

Referring to the drawings more particularl it will be seen that the piston, which is pre erably formed of lightweight material such as an alluminum alloy, com rises a head 10 and a skirt 11, the upper en of the skirt being separated from the head by slots 12.

over the $eater part of the piston circumference. iers 13 extend downwardly from the head and are connected at their lower ends to the circular part 14 of the skirt, the piers roviding integral, homogeneous connections tween the head and the skirt. A piston pin boss 15 is formed in the intermediate portion of each in.

The cylin er-bearing portions 16 and 17 project upwardly between the piers from the circular end 14 of the skirt, and the upper ends of these cylinder-bearing portions are connected by struts 18.. which are formed of a material less expansible than the material of the skirt, such as steel. Each of the struts has one of its ends embedded in the bearingportion 16 and its opposite end is buried in the bearing-portion 17, while its intermediate portion is buried in the pier 13. The struts act as spacing and supporting means for the upper ends of the cylinder-bearing portions and have a determining influence on the diametrical expansion of the thrust faces.

In order to stiifen the bottom of the skirt, each side of the skirt is provided below the pin boss with an arc-shaped flange 19 projecting inwardly from the wall of the skirt. A slot 20 extends upwardly from the lower edge of the skirt into the thrust face 16.

. In the piston illustrated in Figs. 1 and 2 the skirt is also braced by a segmental rib 21 which connects the lower end of each pier 13 to the circularpart 14 of the skirt. This rib is omitted in the species of Figs. 3 and 4 and in this case the lower end of each pier connects directly with the lower end of the skirt.

The features of piston structure involved in this invention have a number of important advantages that cooperate to form an improved piston. The reinforcing flanges 19 are located at the very bottom and hence the metal for stifi'ening has the greatest advantage possible, and the piston can be given the maximum amount of stifl'ness with the minimum weight of metal. Due to the fact that these flanges are arc-shaped and are spaced from each other they do not interfere with the production of the piston in a permanent mold with a simple three-piece core. Fig. 5 clearly illustrates how these flanges 19 may be formed in the sector cores only. Upon completion of the molding operation the center core 22 can be slid vertically out of the piston, after which the sector cores 23 can be collapsed toward each other to disengage them from the flanges 19.

The flanges 19 have an important function in supporting the sides of the skirt during the machine operation, and thereby facilitate production machining. Also since the skirt has the flanges on the inside which may be bored out for machining purposes, the skirt wall may be made thinner than is conventional as no boring has to be done taking metal out of the inside of the skirt at the bottom.

The slot 20 may be cut of such a length that in conjnnction with the skirt-stiffening means it will produce a skirt having the same stiffness perpendicular to the piston pin as parallel to the pin, i. e., to give equal deflections for equal loads at AA or BB (Fig. 5). or any desired ratio for these deflections.

The semi-circular flanges 19 help to maintain the true circular shape of the skirt and prevent binding of the skirt below the pin bosses, while the break in the flanges at 24 in Fig. 2- and 4 renders the skirt flexible enough to permit closing in of the slot.

The diagram of Fig. 6 shows the effect of the various stiffening means at the bottom of the skirt on the piston expansions, line E representing the normal skirt diameter. If the piston is provided with a strong predominating rib 21 and the flanges 19 are omitted, the skirt will expand along line C (the zone of rib 21) to the extent indicated, and since the upper end of the skirt is tied in by the struts 18, the lower end of the skirt will be carried out to the points F. On the other hand, if the ribs 21 are omitted leaving the skirt relatively weak in this zone, and if strong flanges 19 are used, the skirt will expand along line D (the zone of flanges 19) to the extent indicated, and the lower end of the skirt will expand considerably less than in the first case, being carried out only as far as the points F'. 7

Figs. 7 and 8 illustrate diagrammatically how the spacing of the strut from the upper end of the skirt can be varied in order to obtain different skirt action under changes of temperature. In Fig. 7 the strut is placed at the extreme upper end of the skirt. With this construction, as the piston becomes chilled on a very cold day the diameter B contracts While diameter A is held out by the struts. In Fig. 8 the struts are placed lower down nearer the middle of the skirt. In this case as diameter B contracts diameter A increases and becomes larger than diameter C at the strut. In this case the close fit on diameter A will compensate for the looser fit on diameter B, and will keep the piston from slapping. These pistons operate injust the reverse fashion as the pistons are raised above normal temperature. Each of these strut spacings is suitable for a certain set of conditions.

I claim 1. A piston comprising a head, a skirt connected to the head, and a pair of arc-shaped flanges extending inwardly at the bottom ofthe skirt, said flanges being spaced from each other and located on opposlte sides of the piston.

2. A piston comprising a head, a skirt connected to the head, a pair of thrust faces formed on the skirt, and a pair of arc-shaped flanges extending inwardly at the bottom of the skirt, said flanges being spaced from each other and each flange extending along the skirt wall from one thrust face to the other.

3. A piston comprising a head, a skirt connected to the head, piston pin bosses, thrust faces located between the pin bosses, a pair of arc-shaped flanges extending inwardly at the lower end of the skirt, each flange being below a pin boss, and one of the thrust faces being formed with a slot extending upwardly from the lower edge of the skirt between the flanges.

4. A piston com rising a head, a skirt connected to the hea piston pin bosses, thrust faces located between the pin bosses, a pair of arc-shaped flanges extending inwardly from the bottom edge of the skirt, the lower central portion of each thrust face bein left unflanged, and one of the thrust faces eing formed with a slot extending upwardly from the lower edge of the skirt into the unflanged portion.

5. A piston comprising a head, piers depending from the head, a circular portion connected to the piers, thrust faces extending upwardly from the circular portion, said thrust faces being formed of light-weight material, struts connecting the upper ends of the thrust faces, the struts being formed of material less expansible than that of the thrust faces, and a pair of arc-shaped flanges extending inwardly at the bottom of the skirt,

Ill

said flanges being spaced from each other and located on opposite sides of the piston.

6. A piston comprising a head, piers depending from'the head, a circular portion connected to the piers, thrust faces extending upwardly from the circular portion, said thrust faces being formed of light-weight material, struts connecting the upper ends of the thrust faces, the struts being formed of material less expansible than that of the thrust faces, and a pair of arc-shaped flanges inwardly from the bottom edge of the circular extending inwardly at the lower end of the than that of the thrust faces said struts being skirt, said flanges being spaced from each located at the uppered 'eso the thrust faces,

other and located on opposite sides of the each strut being buri iston, and one of the thrust faces being ormed with a slot extending upwardly from tflhe lower edge of the skirt between the anges.

- 7. A piston comprising a head, piers depending from the head, a circular portion connected to the piers, thrust faces extending upwardly from the circular portion, said thrust faces being formed of light-weight material, struts connecting the upper ends of the thrust faces, the struts being formed of material less expansible than that of the thrust faces, and a pair of arc-shaped flanges extending inwardly from the bottom edge of the skirt, the lower intermediate .portion of each thrust face being'left unflanged, and one of the thrust faces being formed with a slot extending upwardly from the lower edge of the skirt into the unflanged portion.

8. A piston comprising a head, piers depending from the head, a horizontal segmentshaped rib formed on the lower end of each pier, a circular portion connected to the ribs anda pair of arc-shaped flanges extending portion. 7

9. A piston comprising a head, piers depending from the head, a horizontal segmentshaped rib formed on the lower end of .each, pier, a circular portion connected to the ribs, thrust faces extending upwardly from the circular portion, said thrust faces being formed of light-weight material, struts connecting the upper ends of the thrust faces. the struts being formed of material less expansible than that of the thrust faces, and a pair of arc-shaped flanges extending inwardly from the bottom edge of the circular portion.

10. A piston comprising a head, piers depending from the head, a horizontal segmentshaped rib formed on the lower end of each pier, a circular portion connected to the ribs, thrust faces extending upwardly from the circular portion, said thrust faces being formed of light-weight material, struts connecting the upper ends of the thrust faces, the struts being formed of material less expansible than that of the thrust faces, a pair of arc-shaped flanges extending inwardly from the bottom edge of the circular portion, the lower central portion of each thrust face being left unflanged, and one of the thrust faces being formed with a slot extending upwardly from the lower edge of the skirt into the unflanged portion.

11. A piston comprising a head, piers depending from the head, and having pm bosses formed therein, a circular portion connected to the piers, thrust faces extending upwardly from the circular portion, said thrust faces being formed of hght-weight material, and a pair of struts of material less expansible In testimony in one of the piers.

ature.

DISCLAIMER 1,830,172.Ad0lph L. Nelson, Detroit, Mich. PISTON. Patent dated November 3,

1931. Disclaimer filed January 9, 1939, by the assignee, Balm Aluminum ab Brass Corporation.

Hereby enters this disclaimer to clailn 1' of said patent.

[Ofiicial Gazette February 7, 1939.]

DISCLAIMER 1,830,172.Adolgi r L. Nelson, Detroit, Mich. PISTON. Patent dated November 3,

1931. lsclaimer filed December 29, 1939, by the assignee, Balm Aluminum (5: Brass Corporation. Hereby enters this disclaimer to claims 2, 3, and 4 of said patent.

[Ofiicial Gazette January 23, 1940.] 

